This invention relates to a process for preparing catalyst containing, sulfur-solvent compositions wherein such compositions are treated, before, during or after incorporation of said catalysts, to inhibit the deleterious effects of impurities. More particularly, it relates to a process wherein sulfide-containing, sulfur solvents are treated with primary or secondary amines whereby the catalyst poisoning effects of impurities in the solvent are inhibited.
In the processing of sour gas wells, sulfur may form deposits that can plug the well and terminate production. These deposits have been prevented or minimized by flowing solvents such as carbon disulfide, organic solvents, and aqueous alkylamines (U.S. Pat. No. 3,545,916), downhole. The solvent is injected and the well is allowed to soak for a sufficient period of time to dissolve any existing sulfur plugs. Alternatively, the solvent can be injected continuously in amounts sufficient to prevent the formation of sulfur deposits.
Dialkyl disulfides, either alone or blended with dialkyl sulfides (U.S. Pat. No. 3,531,160), have become the sulfur solvents of choice. Hyne [Alberta Sulfur Research Ltd. (ASRL), Quarterly Bulletin, vol. XVIII, Nos. 2, 3, and 4, 1982, p. 44] has shown that lower dialkyl disulfides, especially dimethyl disulfide (DMDS) are preferred. Alone they take up only a limited amount of sulfur; however, in conjunction with a suitable catalyst system, they will take up approximately 1.5 times their weight in sulfur at room temperature.
Impurities which may occur in the sulfide-catalyst compositions referred to above will poison the catalyst and prevent it from improving the ability of the composition to take up or dissolve sulfur. These impurities, including carbon disulfide and alkyl mercaptans, are formed within the dialkyl disulfide or polysulfide during manufacture. In addition, when these compositions are injected into a sour gas well they are exposed to impurities from the well gas stream which impurities, including carbon disulfide and carbon oxysulfide, are increased as the bottom-hole temperature and pressure increase (Hyne, J. B. et al., World Oil, 1980, October, 111). In wells which contain high amounts of carbon disulfide and carbon oxysulfide, the catalyst in the sulfide compositions may react with these impurities and become poisoned.